Connecter-switch circuits



Patented June 26, 1928.

UNITED STATES 'PATENT OFFICE.

JOHN XVICKS, F OAK PARK, LLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTSfTOAUTO- MATIC ELECTRIC INC., 0F CHCAGO, ILLNOIS, A CORPDRATION OFDELAWARE.

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`comanornia-SWITCH` CIRCUITS.

Original application led .Tune 3,1922, `Serial No. 565,734. Divided andthis application tiled April `17, Y1925, serial No. 23,754. Renewedoctober 19, 1927.

The present invention relates to automatic telephone systems in general,but is concerned more particularly with the provision of certain novelcircuit arrangements to be employed in connection with the connecterswitches, which are the switches that finally complete the connectionsbetween calling and called lines in automatic telephone systems.

According to one feature, a novel'circuit` arrangement has been devisedsuch that the wiper-switching relay of the connecter switch 1scontrolled over the called line. rThis 1s `done to prevent itfromenergizing to connect up rthe wipers and thereby project out ringingcurrent until the cut-ott1 relay of the `called line has pulled up to`disconnect the line relay `of the line switch on the called line vtroniin bridge of the called line.

According to another feature o'l" this case, circuit arrangements areprovided whereby the connection between the release trunk conductor andthe guarding ground contacts of the switching relay is altered, so thatthe test w-indino oi' the switchin@r relais ea;-

eluded "from the `guarding' circuitwhile the `connecter switch isbeing'lheld by the cal-led line after the calling' subscriber' hasreplaced his receiver. Another point in connection with this arrangementis that the test winding,l oi' the switching -relay is not merelyshorted but the connection to the release tri-ink conductor is shiftedfrom one termi` nal ofthe test windinplr tothe other, leaving the testwinding open so that it will not' `make the relay slow to release. i

" Accordingto still another feature, the circuit of the release magnetis taken through nornnilly closed contacts on the switching relay soaslo prevent the operation of the rel .e magnet before the switchingrrelay Referringnow to the aceompanyine,r draw'` ingr, comprisinga singlesheet, `this drawing shows-thc connecter ll, to which the foregoingfeatures of theinvention are applied,

,togctherrwith the line switch Cand lthe as- .so-elated line coming intothe exchange from the substation A.

F rom a mechanical standpoint the connecter H is oi the .usual verticaland rotary type of switch, having its bank contacts ar- 00 raneedinhorizontal rows or levels.

he line switch C is, from a `mechanical standpoint, a switch of the wellknown ro tary type having wipers which are advanced upon the backstrolce of the associated step- 05 pingr magnet and which have no normalpo sition.

` The substation A, it may be pointed out,

is of theusual common battery type and has a calling device forcontrolling the auto-.70 matic switches in addition to the other wellknown parts.

It will be noted that relay 4:05 of the conf necter H is labeled Twostep. This is to indicate that the relay operates part way `only underone condition and that it operates fully under another condition. Inorder to dill'erentiate between the contacts which are operatedupon thefirst step of the relayand those which are operated upon 8.0 the secondstep `of the relay, those contacts which close when thc relay isVoperated through its first step only are indicated by the numeral 1,and those contacts which are 'operated yonly in case the lrelay operatessa through its second step are indicated by the numeral. 2.` y

The invention having been described more orless generally, a detaileddescription of the operation of the `apparatus shown will 9o now begiven. For this purpose it will be assumed that a subscriber on acalling;r line (not shown) desires to communicate with the subscriber'at substation A. lt will be 'assumed lurtherthat, when the calling sub#95 scriber removes his receiver and dials the y .first twodigits. thethousands `selector seized by the calling line switch seizes a hundredsselector' in the :thousands group in which the connecter H is` located`andthat the 10o seized hundreds selector raises its wipers opposite Vthelevel of bank contacts in which the trunk line 'leading to the connecterH and comprising conductors S- 382 terminates. It will be assumedfurther that the trunk line leading to the connecter' H is the the lineswitch included in the connection.v

The calling subscriber may now operate his calling device for the nextdigit of the desired number. By this operation a series of interruptionsis produced in the circuit of line relay 401 of the connecter H, whichrelay deenergizes a plurality of times in response thereto. At the firstdeenergization, a circuit is completed extending from ground by way ofarmature 418 and its back contact, armature 421 and its front contact,otl' normal springs 422 and 425, winding of the slow acting relaiy 403,and thence through the winding of the vertical magnet 409 to battery.The vertical magnet 409 operates to raise the wipers 450-452 step bystep until the said wipers are brought opposite the level of bankcontacts corresponding to the number of interruptions in the digitdialled.

Upon the first vertical step of the switch the off normal springs areshifted with the resultl that the last part of the first impulse and allof the remaining impulses to the vertical magnet traverse a new circuitwhich is the same as the one traced above except that it includes offnormal springs 422 and 423, and armature 424 and its working contactinstead of off normal springs 422 and 425, the slow acting series relay403 being now energized. Relay 403, being slow acting, is maintainedenergized throughout thev series of impulses delivered to the kverticalmagnet 409.

At the termination of the series of impulses relay V403 deenergizes,thereby transferring the impulsing circuit to the rotary magnet 410.

The calling subscriber may now dial the next and final digit in thedesired number. As before, a series of interruptions is produced in thecircuit of line relay 401. At each retraction of armature 418 on linerclay 401 an impulse of current is sent to rotary magnet 410, the pathat the time of the first closure being as follows: from ground by way ofarmature 418 and its back contact, armature 421 and its front Contact,olil normal springs 422 and 423, armature 424 and its back contact, backcontact and armature 431, armature 441 and its back contact, and rotarymagnet 410 to battery. The rotary magnet 410 operates to rotate theswitch wipers into engagement with t-he set of bank contacts associatedwith the line of substation A. The slow acting relay 406 is energized inmultiple with the rotary magnet. At armature 433 relay 406 disconnectstest wiper 451 from the test Winding of relay 407,

and connectsit instead to the test winding of busy relay 405, througharmature 440 and its bacl; contacts, and at armature 434 this relayshort circuits the back contact and armature 431 on the test relay 405.This latter operation, serves to preserve the continuity of the rotarymagnet circuit while the switch wipers are being rotated over bankcontact sets associated with busy telephone lines.

At this point it may be well to explain something of the function andmanner of operation of the upper winding of the twostep relay 405. Itwill be noted that except for the upper winding and certain addedcontacts, this relay is the usual busy relay, and that the armatures4304132 are the usual armatures found on the busy relay of an ordinaryconnecter switch. In the present case, however, this busy relay has afurther function, and that is to prevent the premature energization ofswitching relay 40T by maintaining the upper winding of the latter relayshort circuited at armature 429 until the bridge-cutoff relay of theline switch on the called line pulls up to disconnect the line relay,This, yit will be seen, is to prevent the false operation of the linerelay from the ringing current which is to be applied to the calledline, or, in case the private normal conductors of the called line arereversed, to prevent a premature energization of the ring-cut-of'1 relayof the connecter, which relay (in this latter case) would energize fromthe normal ground potential on the lower line conductor.

The arrangement for accomplishing the result-s above set forth includesthe bridge across line wipers 450 and 452 through the upper winding ofrelay 405, armature 428 and its resting contact, working contact andarmature 414 of line relay 401, and the resting contact and armature435.y This bridge, it will be noted, includes contacts on the line relay401. Accordingly, each time line relay 401 pulls up follmving adeenergization to operate rotary magnet 410, it connects the upperwinding of relay 405 in bridge of the line wipers 450 and 452 unless theline encountered by the wipers is busy, in which case relay 405 willhave operated through wiper 451, and the bridge including the upperwinding of the relay is open at armature 42S. From this it follows that,if the line to which the wipers are advanced upon any one of theoperations of rotary magnet 410 is idle, relay 405 does not energizethrough its lower winding, and the bridge through the upper windingremains closed across the line wipers. This upper winding of the relayis a high resistance winding so as to prevent the operation of the linerelay of the idle `lay `is operated :through its `operates throiigh itsiirst step and places a shunt around the upper winding of relay 40T toprevent the operation of the latter relay for the ltime lieing,withoutperforming any of the other functions ofthe relay, which other functionsare ,performed only 'when Vrelay 405 1is acting in its capacity as aIbusy relay..

Assuming'Y -that the desired 'line is busy when the wipers -ot' theswitch land upon the associated bank contacts, as pointed out above,there isa ground potential present on the test contact 455engaiged by`test con` tact ffl-l, and the test relay 405 is energized. Uponoperating relay V405 at armature 430 establishes a point in its lockingcircuit which is completed upon the subsequent deenergization of theslow acting relay 40G; at

ari'nafturc 420 it short ycircuits the upper winding of relay 407:5;` atarmature 428 it opens the circuit t'or its `own upper winding; atarmature 431 itopens apoint "in the circuit of the rotary magnet; and atarmature 432 it `connects 'a lead from the busy machine `to the `lowertalkingconductor. This latter action results in the transmission oit anaudible ytone to the calling subscriber whois thus `notifievcl that thedesired l-ine is busy, and he will replace his receiver 1upon cheswitchhook, thereby initiating the release of the operated switches `ina i-malnner which will be `described later.

llt will now ybe yassumed that the line `of the substation A is idlewhen the .Wipers 450w 452 are brought into `connection with the bankcontacts 454-456;` 'Under these `conditions there will be no groundconnected to testcontact 455, and nofcircuit is completed for the lowerwinding lof test relay 405. Accordingly, the upper windingol relay 405remains bridged across theline Wipers, with the result that the relayoperates through its first step only and shuntsthe upper winding otrelay 407 at armature 4429. Then, when, upon the deenergization of theslow acting `rch-1y"40G, `the circuit is completed extending. 'from`ground on release trunk conductor `381 by Way of armature 430 and itsback contact, normally closed springs controlled by armature 437 upperwinding of the switching relay 407, back contact and armature 433, testwiper 451, test lContact455, winding `of the switching relay 470 of theline `switch C', and thence to batteryfthrough`the winding of the rotarymagnet 474, relayw407 remains inert because its upper winding shortcircuited at armature 429.

The rswitching relay 470 `of the line switch C energizes over itsabovetraced circuit to disconnect the normal battery and round connectionfrom the called lne in tlie line switch C. This latter operation opensthe `circuitof the upper winding fof the test relay 405 whichdeenergizes `so as to remove the short circluit from around the `upperwinding ofV the relayj407 Relay 407 thereupon energizes andfat itsarmature y439 establishes a `locking circuit for its; lower wind-ing;opens a point in the circuit of the lower winding of busy `relay 405'atarmature 440; disconnects `rot-ary magnet 410` at armature 441; .opensal pointjin the `circuit of release magnet 408 at armature 442; replacesdirect groundvon test wiper 4511alt armature 438; closes the ring-backtone circuit at armature 436i; disconnects the vback contact of armature1430 from the Aupper terminaloi relay 407 and connectsitto the lowerterminal at armature V437; andat ar'- matures 435y and 443 connects yupthe line wipers 450 and452, at the same time `disconnectingthe upperwinding 'of relay 405 from 1in bridge ofithe said 'line wipers.

Ringing current `from lthe generator GEN. is now intermittentlyprojected "out through the jupper winding of the 'ring-cut-olt relay404, and 1through wiper 450 to the called line to ring the bridged bellatsubstation A', and it returns over the lowertalking conductor toground through the back con tact of armature `427. i i

`When the 'subscriber at substation A respondsito :the `ri'rnging oft'his bell by frei movin-g his receiver, ring=cutioff relay 404 energiz'es'overlhis lline; closes a 'locking Icircuit for itself at armature 426;and a'tarlnatures 425 and 427 disconnects wipers 450 and452 ifrom thegenerator lead and Iground and connects them to the windings ot thedouble wound back bridge relay 400. Relay 400 now energizes over thecalled line and places a multiple ground 'on the llocal lockingconductor at armature 41:15; and at armature 416 and 417 reversesthelconnection of conductors `380` and 382 to `ljine relay 401, there#by reversing the direction of ictn-rent flow in the callingline. y Thislatter operation is standard practice and is utilized in some casesto`operate meters, give supervision, andthe like. y

The `calling `and called subscribers may now converse with each otheras'desired land when the yconversation -is `terminated they both replacetheir receivers. y p Assuming that the `-subscriber ,at substation Areplaces 'his receiver hist, back bridge relay '400 falls back anddisconnects at *armature 415 the "second Lgroulncl conneclil() tion fromthe local locking conductor, and at armatures 416 and 417 reverses thecurrent How in the calling line back to normal.

When the calling subscriber replaces his receiver line relay 401 fallsback and closes the usual impulse circuit at armature 418 and its backcontact. Rotary magnet 410 does not respond at this time on account ofthe fact that it is disconnected at armature 441 of relay 407. The slowacting relay 406, however, pulls up overthe impulsing circuit anddisconnects the release trunk concircuit of slow actingrelay 406 andprepares a. circuit for release magnet 408, which circuit, however, isstill maintained open at armature 442 of switching relay 407. Atarmature 419 relay 402`disconnects ground from the local lockingconductor whereupon the ring-cut-off relay 404 and switching relay 407both fall back, and relay 407 completes at armature 442 the circuit ofthe release magnet 408 through the upper pair of olf normal springs.Release magnet 408 now energizes and restores the wipers 450-452 totheir normal position in the usual manner. The circuit of release magnet408 is opened at the off normal contacts when the switch shaft attainsits normal position. Relay 406 now falls back, but it does not groundrelease trunk conductor 381 because relay 407 has restored.

For the purpose of illustrating the feature of the invention having todo with guarding the connecter H while it is held by the called party,it will now be assumed that the calling subscriber replaces his receiverbefore the subscriber at substation A replaces his receiver. That beingthe case, line relay 401 falls back as hereinbefore pointed out when thereceiver is replaced at the calling subst-ation, opens the circuit ofVrelay 402, and l closes a circuit for relay 406. Accordingly, relay 406energizes as before and disconnect-s the grounded `test wiper 451 fromthe grounded release trunk conductor at armature 433. A moment laterrelay 402 falls back and disconnects ground from release trunk conductor381 at armature 420, allowing the line switch and selectors to releasein the usual manner. At arma-ture 419 relay 402 removes ground from thelocal locking conductor, but operation is ineffective at this time onaccount of the fact that this conductor is maintained grounded atarmature 415 of back bridge relay 400. As afurther result of itsdeenergization, relay 402 opens the circuit of relay 406, as before, andprepares the circuit of release magnet 408. After the usual interval,relay 406 falls back and again connects the grounded wiper 451 torelease trunk conductor 381 at armature 433 and its back contact,through armature 437 and its front contact, and the back contact andarmature 430. This operation serves to guard the connecter H againstseizure. Y

When the subscriber at substation A replaces his receiver, back bridgerelay 400 falls back and removes ground from the local locking conductorat armature 415, thereby unlocking relays 404 and 407. lVhen relay 407falls back, it removes ground from the release trunkconductor and fromthe private wiper 451 at armature 438, and at armature 442 completes thecircuit of release magnet 408, whereupon the switch is lrestored to itsnormal position in the usual manner.

What is claimed is:

1. In a telephone system, a telephone line, a connecting circuit, meansfor extending a connection through said circuit to said line, a relay insaid circuit toV complete the connection to said line, anelectro-magnetic responding device connected to said line, meanscontrolled by the extension of the `connection to said line fordisconnecting said device therefrom, and means for preventing theenergization of said relay until such disconnection is effected.

2. In a telephone system, a telephone line, an automatic switch forextending a connection thereto, a relay in said switch adapted tocomplete the extension of connection to said line, a battery connectionon said line, means controlled by the extension of the connection tosaid line for removing said battery, and means for preventing theenergization of said relay until said battery is removed.

3. In a telephone system, an automatic switch, a telephone lineaccessible thereto, means for operating said switch to extend aconnection to said line, a relay in said switch for completing theconnection, and means operative to delay the energization of said relayfor a predetermined time.

4. In a telephone system, an automatic switch, a telephone line, meansfor operating said switch to extend a connection to said line, a linerelay and a cut-'olf relay for said line, a source of ringing current, arelay in said switch for connecting said source to said line, means forcompleting a circuit for said cut-oil' relay when the connection isestablished to energize said cut-olf relay to remove the associated linerelay from in 0011- y 1,675,312 i v nection with the line, and a secondrelay in said switch energized in series with said line relay when theconnection is completed to prevent the operation of the first mentionedrelay until the said cut-oft relay has operated.V

5. In a telephone system, a plurality of telephone lines, each linehaving a talking conductor anda test conductor, an automatic switchhaving `a test wiper and a line wiper, a line relay and a steppingmagnet for 'said switch, a circuit including normally closed contacts onsaid line relay for operating said stepping magnet to bring said wiperssuccessively into engagement with the respective conductors of saidlines when a desired one of said lines is called, a busy relay connected`to said` test wiper during the stepping operation of the switch, and atest relay winding connected to said line wiper during the steppingoperation through normally closed contacts on said busy relay andthrough normally open contacts on said line relay.

'6. In a telephone system, an automatic switch having a line wiper and atest wiper,

a test relay winding connected to said line wiper, means for bringingsaid wiper successively into engagement with the contacts of telephonelines, and a busy relay operated through said test wiper when aV busyline is encountered for disconnecting said test relay winding from saidline wiper.

7 In a telephone system, an automatic switch having a line wiper and atest wiper, a test relay winding connected to said line wiper, means forbringing said wiper successively into engagement with the., contacts oftelephone lines, a `busy relay operated throughsaid test wiper 4when a.busy line is encountered for disconnecting said test relay winding fromsaid line wiper, and contacts opened during the advance of said wipersfrom one line to another to disconnect said test relay winding from saidline wiper to prevent the closing of the test relay winding circuit to abusy line before the busy relay can be operated.

8. In a telephone system, a connecter switch having line and testwipers, a test conductor for said switch, a relay for connecting saidline wipers to said switch, a winding on said relay having one terminalconnected to said test wiperand having the other terminal connected tosaid test con-` ductor, a circuit for operating said relay by means ofsaid. winding by current flow from said test conductor through saidWinding and through said test Wiper, contacts on said relay closed whenit pulls up to connect up said wipers for placing a guarding potentialdirectly on said test wiper, and

other contacts for opening the connection between said test wiper andsaid test conductor y through said winding and for establishing .a newconnection between said test wiper and said test conductor exclusive ofsaid winding.

9. In a telephone system, a telephone line, automaticl switches forextending connections to and from said line a cut-off relay associatedwith said line operative when the line is called to disconnect theautomatic switch used for extending calls from said line, meansassociated with the automatic switch used in extending a connection tosaid line for transmitting ringing current thereto, and means forpreventing the transmission of ringing current to the line until aftersaid cut-ofiI relay has been operated.

10. In a telephonesystem, a line, an automatic swltch for extending aconnection and transmitting ringing current to said line, line` andcut-olf relays for said line, the line relay being normally connected tothe line, and means for operating the said cut-olf relay to disconnectthe line relay when the line is seized and vprior to the time ringingcurrent is transmitted to the line.

11. VIn a telephone system, a line, a connecter forextending connectionsto said line and for thereafter transmitting ringing current thereto, acut-off relay for said line, and

`line until after the cut-off relay has operated.

13. In a telephone system, an automatic switch equipped with a testwiper, a. test con# ductor for said switch, a relay in said switch,

a winding for said relay having one terminal connected to said testconductor and having its other terminal connected to said test i wiper,and contacts onsaid relay for placing a common guarding potentialdirectly on said test wiper and test conductor.

14. In an automatic switch, a test con-` ductor for guarding the switchagainst seizure when in use, a test wiper, a` rela for placing aguarding potential upon sai test conductor when t-he switch is in use,an o eratingcircuit for said relay including sald Vtest conductor andtest wiper, and contacts on said relay for connecting said testconductor and test wiper together, placing a guarding potential thereon,and for opening said circuit.

In witness whereof, I hereunto subscribe my name this 10 day of April,1925. JOHN WICKS.

